AC is correct to point out that programmer time is more valuable than processor time.

However, that doesn't mean that it's either smart or useful to reimplement the Unix command toolset in Perl. On a busy server, Perl's resource footprint will still trip you up. We have had to reimplement a number of small Perl tools in sh, awk or C by virtue of the fact that even with a half-gig of RAM, we cannot afford to spawn fifty Perl processes every second.

Perl is still a great tool for a lot of our applications. Just not all of them. It might be fun to rewrite zork in Perl, but we're still going to be using good old-fashioned egregious GNU tools for getting real work done.